Mary Bales has faced vilification since being caught on CCTV camera putting a cat in a wheelie bin. Photograph: Rui Vieira/PA

One inexplicable moment of cruelty when Mary Bale seized a cat and dropped it into a wheelie bin was punished with a modest £250 fine today. But the 45-year-old former bank worker may pay the price for her impulsive act for the rest of her life.

The "cat bin woman" from Coventry became reviled around the world, receiving abusive phone calls and death threats from as far afield as Australia, after what she described as a "split second of misjudgment" – which was captured on CCTV and uploaded to YouTube.

Thousands of people signed Facebook pages claiming "Mary Bale is worse than Hitler" and calling for the "Death Penalty for Mary Bale" as she attracted newspaper headlines from "It's a fur cop" to "Miaow could she?"

The question of why a middle-aged, respectable, apparently cat-loving woman would behave in such a way was not exactly answered in Coventry magistrates court today. But the court heard how Bale was stressed and worried about her ill father, whom she would visit in hospital every day, regularly pausing on her walk home to stroke the four-year-old tabby cat called Lola.

On the evening of 21 August, rather than just fondle the cat, she glanced around twice, opened the lid of a nearby green bin and put the cat inside before walking off briskly to her home three streets away.

The cat was trapped for 15 hours until her owners, Stephanie Andrews-Mann, 24, and husband Darryl, 26, found her the following morning. When they played back footage from a CCTV camera installed to deter vandals outside their home, they discovered the evidence and posted a clip lasting one minute 27 seconds on the internet, appealing for people to help identify the woman.

Confronted by the tabloid press, Bale at first claimed she "suddenly thought it would be funny" to put the cat in the bin. Later, requiring police protection after threats against her, she apologised and called her actions "completely out of character".

Nick Sutton, for the RSPCA, told the court it was obvious that her actions were deliberate. "She plainly looked to see if anyone was watching, which means she was clearly aware of the moral position she was in at that time," he said.

Bale's solicitor, David Murray, said she had "very little recollection" of the incident. "The court will of course be concerned as to why this matter happened. Mary Bale has asked herself the same questions for the last two months, hourly," he said.

"The cat was often on the wall seeking attention and she would stroke it. She cannot explain why her behaviour changed on this occasion."

Later, in a statement, he added: "Despite a lengthy period of soul-searching, she cannot still explain her behaviour but she wishes to repeat her apology to the owners of Lola and bitterly regrets her actions."

Bale, who appeared close to tears in court and admitted a charge of causing unnecessary suffering to an animal, was spared the maximum penalty of six months in prison or a £20,000 fine as the district judge Caroline Goulborn acknowledged the "vilification" she had suffered.

The judge also accepted that Bale was in a "stressful situation" at the time, but said that was "no excuse for what you did".

"It clearly was an irrational and impulsive act that you could not explain and in interview you said that you were mortified. I accept that your remorse is genuine," the judge said. "The media interest in this case has resulted in you being vilified in some quarters and I have taken that into account also."

Bale was fined £250 but was also ordered to pay a victim surcharge and costs, a total of £1,436.04. The RSPCA called it "a very fair decision".

Banned from keeping or owning animals for the next five years, Bale may find her infamy takes as long to fade. After a period signed off work for depression, she has now resigned from her job, unable to face her colleagues again.

Bale's father died last Thursday and, according to her solicitor, she now simply wants to help her bereaved mother. She is unlikely to be left alone to do so, and any support may be as unwelcome as the hatred. As she fled a scrum of photographers outside court, an onlooker shouted: "I love you cat lady. Cat lady you are my hero."